532 University of California Publications in Botany [Vol. 8 



J. G. Agardh, Sp. Alg., vol. 1, 1848, p. 126 ; Thuret, Rech. sur les 

 zoospores, 1850, p. 239 (1851, p. 30, Repr.), pi. 29, figs. 1-4; Setchell, 

 Alg. Prib. Islands, 1899, p. 591 ; Saunders, Phyc. Mem., 1898, p. 163, 

 pi. 31, figs. 8-10, Alg. Harriman Exp., 1901, p. 421; Setchell and 

 Gardner, Alg. N.W. Amer., 1903, p. 243; Okamura, Icon. Japan. Alg.. 

 1908, p. 144, pi. 30. Chorda Lo-mentaria Lyngbye, Hydrophyt. Dan., 

 1819, p. 74, pi. 18, e. 



Seytosiphon Lomentaria, if all the forms referred to it belong under 

 it, is a widespread and variable species. It varies from a centimeter 

 or two to twenty-five or more centimeters in height and from a milli- 

 meter or two up to ten millimeters in thickness. It may vary from 

 clearly cylindrical to decidedly flattened and it may vary from regu- 

 larly or irregularly and pronouncedly constricted (especially in the 

 larger plants) to those with no trace of constriction whatever. It 

 may be covered almost uniformly with gametangia or, rarely, the 

 gametangia may be segregated into distinct and limited sori. The 

 gametangia may be longer or shorter, with variations from two up to 

 twenty-five or more longitudinal uniseriate loculi. It has been the 

 custom to separate the var. complanata Rosenvinge, but this occurs in 

 a major and minor form, as do all the variants with the exception per- 

 haps of the typical form (f. typicus) which is constricted, but while 

 this varies much in size, it never occurs among the true minor forms 

 of the species. The larger and smaller forms of each series of forms 

 differ from one another in the size of the cells of the inner layer, and 

 in the length (absolute and in number of loculi in each longitudinal 

 series) as well as in diameter of the gametangia. In order to coordinate 

 the variables as mentioned above, we have tabulated them in the fol- 

 lowing key, rather to give a view of the combinations of characters 

 than that they should be considered of any definite taxonomic import- 

 ance, since intermediate forms are, by no means, absent. 



Key to the Forms 



1. Plants constricted at intervals, medium to large 1. f. typicus (p. 533) 



1. Plants not constricted 2 



2. Plants cylindrical 3 



2. Plants complanate 5 



3. Plants 6 cm. or more high; interior cells large; gametangia long 



2. f. cylindricus major (p. 533) 



3. Plants less than 6 cm. high; interior cells small; gametangia short 4 



4. Sori covering the frond 3. f. cylindricus minor (p. 533) 



4. Sori restricted, definite 4. f. cylindricus maculatus (p. 534) 



5. Plants large, 6 cm. or more; inner cells large; gametangia long 



5. f. complanatus major (p. 534) 



5. Plants small, less than 6 cm.; inner cells small; gametangia short 



6. f. complanatus minor (p. 534) 



